L10N (Localization) Software

LIBNATSPEC is a collection of functions for requiest various
charsets and locales for host system and for other system.
The library allows applications to be written that are
locale and system independent.

FlexCat is a tool to create Amiga localization catalogs similar to what the good-old CatComp tool does. However, it can also create source and header files for developers and can be used on other platforms (Unix, Windows, etc.)

TM stands for TranslationManager. TM/2 originates from IBM TranslationManager/2 tool and is now available to the open source community. TM/2 is a computer-assisted translation system for translators. See http://www.opentm2.org for more information.

IP2Location C library enables the user to find the country, region, city, coordinates, zip code, time zone, ISP, domain name, connection type, area code, weather, MCC, MNC, mobile brand name, elevation and usage type that any IP address or hostname originates from. It has been optimized for speed and memory utilization.
Developers can use the API to query all IP2Location™ binary databases for applications written in C or supporting static/dynamic library.

this is a preprocessor to provide a "national lang support" before the compile-time and then save a lot of run-time.
it initially intended to process websites to multiply it with the number of human langs but it is simple enough to use more generally